package org.apache.commons.graph.algorithms.elo

import org.apache.commons.graph.DirectedGraph

/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements.  See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership.  The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License.  You may obtain a copy of the License at
*
*   http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied.  See the License for the
* specific language governing permissions and limitations
* under the License.
*/

/**
 * Ranking selector
 * @param <P> the player's type
</P> */
fun interface RankingSelector<P> {
    /**
     * TODO Fill me!!!
     *
     * @param playersRank
     * @return
     */
    fun wherePlayersAreRankedIn(playersRank: PlayersRank<P>): org.apache.commons.graph.algorithms.elo.KFactorBuilder<P>
}


/**
 * Creates a new instance of [DefaultRankingSelector] for gived graph.
 * @param tournamentGraph the graph
 */
class DefaultRankingSelector<P>(
    private val tournamentGraph: DirectedGraph<P, GameResult>
) : RankingSelector<P> {
    /**
     * {@inheritDoc}
     */
    override fun wherePlayersAreRankedIn(playersRank: PlayersRank<P>): org.apache.commons.graph.algorithms.elo.KFactorBuilder<P> {
        //var playersRank = playersRank
        //playersRank = Assertions.checkNotNull(playersRank, "ELO ranking can not be applied if players can not be ranked!")
        return DefaultKFactorBuilder(tournamentGraph, playersRank)
    }
}

fun <P, TG : DirectedGraph<P, GameResult>> TG.eloRate(): RankingSelector<P> = DefaultRankingSelector(this)

fun <P, TG : DirectedGraph<P, GameResult>> TG.eloRate(playersRank: PlayersRank<P>) = eloRate().wherePlayersAreRankedIn(playersRank)

